I am a foreign worker doing my OPT with an F-1 visa. I became a resident alien for tax purposes in 2014.

What I have learned from the IRS website I think I had to start paying FICA taxes in 2014. I contacted my employer about this, and they told me that they won't be able to withhold FICA taxes until I get H1B status. Do I need to do something about this? Are there penalties or interest charges for failure to pay FICA? Thanks.